1. Field of the Invention
The present invention relates to a rotational constructional laser including a housing, a light source for emitting a laser beam and located in the housing, a housing unit at least partially projecting beyond the housing and having a least one beam hole for the laser beam, a laser beam deflection device located in the housing unit, a drive for rotating the deflection device, a device for tilting the rotational axis of the deflection device, a detection device for detecting a return laser beam reflected from a display mark and entering the housing unit through the at least one beam hole, and an evaluation and control unit connected with the detection device and controlling operation of the tilting device in accordance with detection data obtained in the detection device.
2. Description of the Prior Art
Constructional lasers with a rotatable laser beam are primarily used in the constructional industry in installation and electrical handwork and in the associated trades as an auxiliary means for tracing horizontal and vertical lines on floors, ceilings and walls or for defining horizontal, vertical or arbitrary inclined planes in a space. They can be used, e.g., for aligning walls, door frames, windows and for determining the course of lighting installations. A conventional, prior art rotational constructional laser comprises a laser unit located in a housing and the emitted laser beam of which is deflected by about 90xc2x0 by a deflection device. The deflection device rotates about an axis that coincides with the optical axis. Upon rotation of the deflection device, the laser beam, which propagates, as a result of its deflection, transverse to the rotational axis of the deflection device, describes a plane. A servo controlled device tilts the rotational axis of the laser beam in two mutually perpendicular planes in order to compensate the unevenness of the controlled surface or in order to define, if needed, inclination surfaces in a space.
Such lasers are disclosed, e.g., in European Publication EP-A-O 787 972 and EP-A-O 854 351 which describe different laser apparatuses which permit to recognize an error position of a rotational plane with respect to a reference line on a specially formed target plate. Upon occurrence of an error position, in EP-A-O 787 972, a signal is generated indicating to the user the direction in which the apparatus need be pivoted and with which the apparatus need be aligned in order to establish a correct position of a plane defined by the rotating laser beam. In EP-A-O 854 357, a servo system provides for an automatic alignment of the rotational plane of the laser beam in the direction of a reference line traced on a specially formed target plate.
As disclosed in the above-mentioned prior art publications, the conventional rotational constructional laser axis can be tilted in two directions. However, the position of the beam hole insures that the position of the plane remains stationary with respect to the laser. If, e.g., a plane, which is defined by a rotating laser beam should be displaced parallel to itself, the constructional laser itself should be displaced laterally. E.g., it may be necessary to constantly monitor the setting of a horizontal plane, which passes through a height mark on a structure, and to constantly adjust it when the position of the apparatus is unstable. In this case, usually, for height adjustment, the apparatus is mounted on a stativ, rail, or wall bracket. In case an error position is detected, the position of the apparatus is manually readjusted. If the target height mark is spaced from the laser by several meters, which can be the case when the laser is located in a center of a large space, the coincidence of the laser beam and the height mark is not always can be determined from a view point on a laser. In this case, either an auxiliary means need be used for the readjustment of the proper position of the laser, or the user has to run back and forth between the point the laser is located at and the height mark until the laser position is properly readjusted.
In another case of the use of a constructional laser, e.g., a vertical plane need be aligned in a horizontal direction of, e.g., an axis of a structure which is determined by one or two target marks provided on the structure. In this case, the constructional laser is placed on a floor or bottom of the structure and is aligned manually with respect to two marks provided on opposite walls. To this end, one mark is targeted by rotation of the laser about a vertical axis, and then the error position of a plane which is determined by the rotating laser beam, is measured with respect to the second mark. In accordance with the ratio of both deviations of the laser with respect to the two marks, the position of the laser is readjusted by displacing it by the largest distance. This process is repeated as many times as necessary until the plane, which is defined by the laser beam, passes through both marks. In the laser disclosed in the above mentioned publication, tilting of the laser rotational axis about a vertical axis can lead to an automatic alignment with respect to one of the target marks. However, this automatic alignment represents only a partial step of the entire process necessary for an exact alignment of a depictable vertical plane.
In another case of the use of a constructional laser, e.g., during renovation of old structures with generally inclined walls and/or ceilings, it can be necessary to depict a skew plane passing through three target marks provided on a structure. With a conventional laser, this is effected in a way similar to the alignment of a vertical plane with respect to the structure axis. Because there exist a third mark, more testing steps are needed, and the adjustment is effected more gradually.
The three case of the laser use, which were described above, belong to most often cases of the laser user and, with conventional lasers, their use is relatively complicated and time-consuming.
Accordingly, an object of the present invention is to provide a rotational constructional laser which would permit to conduct the readjustment processes, which were described with reference to the three cases of the laser use in a more simple manner, more rapidly, and with more comfort.
This and other objects of the present invention, which will become more apparent hereinafter, are achieved by providing a rotational constructional laser including a light source for emitting a laser beam and located in the laser housing, and a deflection device for deflecting the laser beam. The deflection device is rotated by a motor about a rotational axis of the laser. The deflection device is located in a housing unit that at least partially projects above the laser housing and has at least one laser beam hole for the laser beam. The inventive constructional laser further includes a device for tilting the rotational axis of the deflection device, and a detection device for detecting a return laser beam reflected from a display mark and entering the housing unit through the at least one beam hole. An evaluation and control unit is connected with the detection device and controls the operation of the tilting device in accordance with detection data obtained in the detection device. Still further, the laser includes an automatically actuatable device for adjusting an axial position of the deflection device with respect to its initial axial position in accordance with control signals generated by the evaluation and control unit in accordance with the detection data obtained in the detection device.
With a constructional laser according the present invention, there becomes available a further degree of freedom that simplifies the adjustment of the laser and an alignment with respect to a reference mark provided on a structure. The basic structure of the inventive constructional laser is similar to a basic structure of a conventional laser disclosed, e.g., in U.S. Pat. No. 5,784,155 and incorporated herein by reference thereto.
The present invention adds to the standard components of a conventional laser apparatus, such as sensor components, components responsible for actuation of drives, and elements for adjusting the inclination of the rotational axis, and associated therewith servo systems, an automatically actuatable device for effecting an axial displacement of the deflection device and, associated with the device, elements of the evaluation and control unit.
For adjusting the inclination of the rotational axis of the deflection device, the laser according to the present invention includes three orthogonal level sensors acting in direction of three cartesian coordinates, which are described in more detail in U.S. Pat. No. 5,784,155, in which gravitational switch serves for a rough determination of whether the laser is in a correct horizontal or vertical position. In the case when its sensitive region is sufficiently large, this task can be performed by the level sensors. An angular encoder on the deflection device serves for determining the direction in which the target plate can be seen from the laser. Thereby, the main inclination direction can be established. A detection device serves as a receiver able to recognize a reflection signal from the target plate and the plate coding. The received signal is then transmitted to the evaluation and control unit which determines the actual position of an instant rotational plane with respect to a stationary set position, which is defined by the target plate, and, in accordance with this determination, generates control signals communicated to actuators responsible for adjustment of the inclination of the rotational axis. In addition to the components described in U.S. Pat. No. 5,784,155, the present invention provides an automatically actuatable device for an axial adjustment of the position of the deflection device and modifies the evaluation and control unit so that it can recognize a necessary axial position and can generate control signal necessary for effecting the height or lateral adjustment.
The rotational constructional laser according to the present invention is designed primarily for tasks performed by a constructional worker. The worker solves the problem of depicting a plane in a space when the exit plane of the laser beam does not lie in a zero point of a coordinate system, but not from the point of view of a mathematician who performs a transformation of the coordinate. Rather, the worker procedes with an alignment of the rotational laser for depicting a plane in a space, based on certain elements which remain unchanged during the adjustment and can be realized by simple parallel displacements of the laser.
An often necessary task of the worker consists in depicting and aligning of a vertical plane. In this case, the direction is determined by displacement that should be effected parallel to or transverse to the axis of a structure. The direction of the axis is usually taken at the structure contour and is shifted by a certain amount parallel to the contour and is determined form the project. Parallel shiffing is always effected by taking the normal distance to a building line at two point spaced by a largest possible distance, when possible, at two contours running transverse to the axis. These points generally lie in a diametrical direction to an installation location of the laser. In this case, the installation location of the laser is so selected that the beam hits both marks. The vertical direction is predetermined and/or retained by the laser, so that the laser is not directly arranged in the connection line of the two marks but need only be arranged in a vertical plane passing through this connection line. When the laser according to the present invention is located in a vertical plane, it can register two target marks which can be seen, within predetermined tolerances, with respect to a horizontal and in an opposite direction from the laser. The alignment of the laser is effected by an automatic actuation of the adjusting drives responsible for the adjustment of the inclination of the rotational axis and for the axial height positioning of the laser beam deflection device in accordance with the amount of the laser light reflected form the target marks. The erroneous position is determined by the detected ratio of differently polarized light components of the laser light reflected from different regions of the target marks. If the deviations of both target marks have the same sign, then the axial height adjustment is actuated. As soon as the sign of the deviation of one of the target marks changes or alternates, simultaneously or alternatively the adjustment drives for the adjustment of the inclination of the rotational axis and for the axial displacement of the deflection device are actuated. Thereby, it is insured that one of the target marks would not disappear from the registered region as a result of too early initiation of the inclination of the rotational axis.
A most common task is depicting of a horizontal plane passing through a height mark provided on a structure. Two, different form each other, nonparallel directions in a plane are set based on the horizontality. The third set point is determined by the height mark. At that, the location of the laser on the floor of a structure is so selected that a most possible shade-free scanning of the work area is obtained. The height is manually adjusted by mounting the laser on a telescopic stativ or a wall bracket with a rail guide. The laser retains at that its horizontal alignment, or the horizontal alignment is adjusted automatically. When the laser location need be changed, the height is established again according to the already marked point with respect to the previous location. A so-called shock cut-off takes place in response to rapid excursion of the laser apparatus within a certain tolerance. Thereby, a further error operation, which take place when the laser or stativ is subjected to some inadvertent shocks, is prevented. Slow sinking of the laser apparatus, which take place, e.g., when the stativ is poorly secured, and which could not be recognized and compensated when the conventional lasers were used, can be counteracted when the laser according to the present invention is used. The counteraction is based on the axial height adjustability of the laser beam deflection device. The height mark, with respect to which the laser beam is aligned, remains stationary on the structure during the works in predetermined work field. The position of the laser is controlled by the reflected from the mark, laser beam and is automatically adjusted to an exact height. The adjusted height is retained even if the stativ height, at which the laser is secured, is inadvertently changes. When the stativ is located within the visual region of the height mark, the height of the deflection device of the laser is again automatically adjusted according to the identical reference mark.
A less often case of the use of the rotational constructional laser according to the present invention is depicting of a skew plane through three points defined by target marks on a structure. This case, e.g., can be encountered in all structures. In this case, a plane should represent a xe2x80x9cbest fitxe2x80x9d in the given structures, e.g., a vault, a cavern, a room with an inclined window band, a roof attic, etc. Often, the system is even overdetermined, i.e., the adaptation represents a visual plane over more than three points. While when a conventional laser is used, the solution is only iterative, i.e., is found by a trial and error method, the present invention facilitate the representation of the desired plane. To this end, alternatively, an axial displacement of the rotational axis and an adjustment of the inclination of the rotational axis are effected until the rotating laser beam passes all of the three target marks at the set positions. If two target marks spaced relative to each other by 180xc2x0, have the same sign of the deviation from the set position, an axial adjustment takes place. Simultaneously or intermittently, an adjustment of the inclination of the rotational axis according to the third target mark also takes place. In this way, a disappearance of the third target mark from the scanned region is prevented. As soon as the sign of the deviation of one of the target marks of the set position changes, simultaneously or intermittently, the inclination of the rotational axis in the second direction is readjusted, and a corresponding axial displacement takes place. When both target marks, which are spaced by 180xc2x0 relative to each other, have opposite signs of the deviations, the adjustment of the rotational axis is effected until the sign of one of the deviation changes. In case the third target mark lies closer to that of the two target marks which has an opposite sign of the deviation, this error position is taken into account during the adjustment of the inclination of the rotational axis. Otherwise, this error position remains unnoticed. As soon as the error position with respect to one of the two first-mentioned target marks changes it sign, the adjustment drives responsible for the axial displacement and for inclination in the second direction are readjusted.
Further cases of the use of the invention rotational constructional laser include the following adjustment.
When a target mark for a horizontal alignment of the laser is identified and the error position with respect to this mark is established, the automatic device for axially displacing the laser beam deflection device is actuated. If at the beginning of the axial displacement step, one or two level systems for controlling the inclination of the rotational axis were equalized, i.e., adapted to each other, a respective level system remains active. In this way, a possible leveling error is automatically corrected during and after the axial adjustment.
At the detection of an error position of displayed plane extending transverse with respect to a target marking, the direction of the error position is detected, and the rotational axis is inclined or tilted to such an extent that the direction shows the maximum inclination to this target marking.
When an error position of a horizontally arranged target mark and a vertically arranged target mark are established, the axial displacement and the adjustment of the rotational axis inclination are effected in such a way that the main inclination direction is perpendicular to the direction toward the horizontal target mark. The initial position of the horizontal plane is reliably maintained due to laser beam deflection device remaining at the same height as the horizontal target mark. The initial position of the vertical plane and the basic alignment of the laser are insured when the horizontal target mark is located, within predetermined tolerances, above and below the laser and the associated plane is aligned, by a plumb and the horizontal target mark, in the direction of the vertical target mark.
When at a non-vertical position of the inventive rotational constructional laser, two vertical target marks are scanned, the adjustment drive at least of the inclination adjustment of the rotational axis of the shaft, which is connected with the laser beam deflection device, is actuated until both target marks are located in the set positions. The axial position remains unchanged. In this way a plane is depicted that is skewed, passing through the given position of the laser beam deflection device and both target marks.
The adjustment process is conducted in a timely sequence in such a way that the laser scans the existing target marks with little rotation. When only one target mark or two target marks, aligned with respect to each other at an angle under 90xc2x0, is (are) available, the rotation of the shaft of the laser housing is controlled, preferably, in such a manner that the laser scans only this limited region. In another case, the laser beam performs a complete revolution. Only after the equalization takes place, the laser reacts on a scanning target, in case it is arranged in the beam path. As soon as the scanning target does not obstruct the beam path, the beam again performs a complete revolution. If the beam finds that the original positions of the target marks do not coincide with the equalizing positions, the laser turns to the adjustment mode and perform the equalization or tuning anew.
In accordance with a first embodiment of the present invention, the axial position adjusting device includes a mechanically vertically adjustable stativ the adjustment drive of which is actuated in response to the control signals generated by the evaluation and control unit.
In this embodiment of the invertile laser, the evaluation and control unit is modified to an extent that it is capable of generating control signals, which are communicated to the adjustment drive responsible for the axial displacement, upon detection of error position(s) of one or more target marks.
The connection of the laser with the adjustment drive for the height adjustment of the stativ can be effected in a simple manner by using a connection cable. In the advantageous embodiment of the present invention the stativ has a mounting plate provided with connection contacts. Upon mounting of the laser on the mounting plate the mounting plate contacts are connected with corresponding contacts provided on the laser housing for communicating the control signals, which are generated by the evaluation and control device, to the stativ displacing drive. The contacts provided on the laser housing can also serve, if necessary, for connecting the adjustment drive with the power source.
With this embodiment, a loosely suspended cable and other like elements are eliminated, and a separate power source for stativ drive can be dispensed with. The adjustment drive is supplied with the power from the laser power source. The range of the axial adjustment or of the height adjustment, which can be obtained by using the stativ, amounts to, e.g., from xe2x88x9250 cm to +50 cm.
In accordance with an alternative embodiment of the laser according to the present invention, the adjusting device includes a rail on which the housing is supported in such a manner that the rotational axis of the deflection device extends parallel to the rail. Upon detection of an error position, housing is displaced along the rail in accordance with control signal generated by the evaluation and control unit.
The constructional laser according to the present invention can be mounted on a mounting plate displaceable along the rail. In a preferred embodiment of the present invention, the laser housing is equipped with support rollers and mechanically driven drive rollers which are actuated in response to control signal generated by the evaluation and the control unit. The support and drive rollers facilitate the displacement of the laser itself along the rail which is effected in accordance with the signals generated by the evaluation and control unit. The drive is effected with one or more friction rollers or by using rollers provided with outer toothing and supported on the rail. The axial displacement along the rail is determined by the length of the rail and can be effected within a range of about xc2x150 cm.
In accordance with a further embodiment of the present invention, the automatically actuatable device for axially adjusting the position of the laser beam deflection device is integrated in the laser housing. To this end, the deflection device is mounted on a rotatable platform that is axially adjusted in accordance with the value of a control signal generated by the evaluation and control unit. With this embodiment of the inventive rotational constructional laser, no special additional elements such as, e.g., a rail or a mechanically adjustable stativ, are necessary. Complementary components, which are necessary for effecting the axial adjustment are likewise integrated in the laser housing. The axial adjustment range of the deflection device, in this embodiment of the inventive laser, amounts to +65 mm from the initial position of the deflection device.
The platform with the laser beam deflection device is located in a housing unit projecting above the laser housing. The housing unit itself can be rotated. In this case, a single laser beam hole is aligned with the non-deflectable laser beam. In the preferred embodiment, the platform is height-adjusted within the housing unit. The housing unit has a shape of a lantern and is fixedly connected with the housing. The embodiment is very robust because the rotatable shaft inside the lantern is protected against jolts.
In order to be able to rotate the laser beam without any obstacles, the lantern-shaped housing unit is provided with four laser beam windows extending substantially in the axial direction. In order for the deflected laser beam to be able to exit the lantern-shaped housing unit over its entire axial displacement path, the windows have a height larger than the entire possible displaceable path. Advantageously, the window height amounts to from about 150 mm to about 160 mm. With such a window height, the adjustment path of +65 mm from a center position can be realized without any hindrance.
In order to provide for a plumb beam, which runs transverse to the deflected laser beam, advantageously the lantern-shaped housing unit has a further laser beam hole arranged substantially transverse to the rotational axis of the rotatable shaft. In this case, the deflection device is formed as a beam splitter to provide for a plumb component of the laser beam.
For the sake of stability, the platform for the deflection device is supported at three points. At least one of the support points is formed by an axially extending threaded spindle that cooperates with the adjusting motor. The threaded spindle provides for a precise axial adjustment. The rigidity of the system is increased and an inadvertent tilting of the deflection device-carrying platform can be prevented when all of the three support points are formed by axially extending threaded spindles which are synchronously displaced by the adjusting motor in accordance with a control signal generated by the evaluation and control unit.
An input keyboard, which is provided on the laser housing, permits to adapt the operation of the evaluation and control unit to specific requirements, e.g., the keyboard permits to change the priority of the inclination adjustment and the axial adjustment. The keyboard can also be used for turning off, if needed, a particular adjustment mode(s).
In accordance with still further embodiment of a rotational constructional laser according to the present invention, a second light source is arranged within the laser housing. There is further provided a second deflection device for deflecting a light beam emitted by a second light source. The second deflection device is located in a second housing unit likewise projecting beyond the laser housing and having at least one beam hole spaced by 90xc2x0 with respect to the at least one beam hole in the first housing unit.
The laser in accordance with this embodiment is capable of depicting, if needed, simultaneously two planes in a space. In a particular preferred embodiment of such double head rotational constructional laser, the position of the second deflection device is likewise automatically axially adjustable along its rotational axis. The adjusting components for the axial adjustment of the second deflection device correspond to the like components for the axial adjustment of the first deflection device.
When the laser beam deflection device is formed as a pentaprism, small deviations of the rotational axis of the pentaprism with respect to the optical axis are easily compensated. This simplifies the adjustment during the assembly of the laser and permits to compensate some shifting of the components that can take place as a result of jolts to which the housing may be subjected. The pentaprism can be formed, if needed as a beam splitter in order to provide unhindered passing of a portion of the laser beam while the second portion of the laser beam is deflected by 90xc2x0.
In accordance with a further advantageous embodiment of the present invention, the device for axially adjusting the position of the deflection device is equipped with end sensors. When the apparatus reaches the limit of the adjustment region, an optional and/or acoustic alarm signal is emitted. The alarm signal is also emitted when the rotational axis passes beyond the limits of the adjustable inclination angle. The laser preferrably is equipped with devices, e.g.; optical or acoustic alarm means that indicate to the user of the laser that a number of target marks or a combination of target marks, which leads to redundancy and, therefore, to contradictory results, has been detected.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.